The present preferred embodiment concerns a printer or copier with a refrigerator for generation of cold. The printer or copier comprises at least one printing unit that generates at least one toner image on at least one side of a carrier material. The printer or copier has at least one fixing unit for fixing of the toner image on the carrier material with the aid of the heat generated by the fixing unit. The preferred embodiment also concerns a method for generation of cold with the aid of a printer or copier.
Modern high-capacity printing systems are known in which printing units generate toner images on a carrier material with printing speeds of up to 1.5 m/sec. The toner images generated on the carrier material must subsequently be fixed at the same speed. If the carrier material is printed two-sided, i.e. toner images are generated both on the front side and on the back side of the carrier material (advantageously with the aid of two printing units), both the toner image on the front side and the toner image on the back side of the carrier material must be fixed with the aid of a fixing unit. In typical high-capacity printing systems, radiant heat is used for supply of the necessary fixing energy given a heat fixing, and alternatively heated rollers are used given a heat/pressure fixing. Combinations of these methods for fixing are possible. Dependent on the width of the carrier material and the actual print speed, such fixing units have an emitted heat capacity of 5 kW to 20 kW. If such a high-capacity printer is operated in an operating mode in which single sheets are respectively printed on one side with the aid of two printing groups, whereby the single sheets to be printed in succession are alternately supplied to the first and to the second printing group, and subsequently, successively directed through a fixing unit, these single sheets are supplied to the fixing unit for fixing with double the printing speed. Depending on the width of the carrier material to be printed and on the print speed of the individual printing groups, a fixing heat capacity of >20 kW can also be necessary in such printer or copiers.
Alternatively, flashbulb fixing devices be used. Given flashbulb fixing devices, the necessary fixing energy is fixed both via the light radiation and via the heat energy generated with the generation of the light energy.
On the other hand, the carrier material is to be cooled and humidified after the fixing in order to not excessively strain (i.e. to stress) the paper. Modules for image generation as well as electronic modules in high-capacity printers also typically have to be cooled. Thus, for example, an LED character generator is cooled or kept at a constant temperature so that the LEDs of the character generator have a uniform light power. The photoconductor temperature may also not be exceeded, since otherwise the conductivity of the photoconductor layer increases, whereby the image generation process would be negatively influenced. The temperature in the developer stations may also not exceed an allowable limit value, since otherwise the toner particles too strongly adhere with other toner particles and with carrier particles, whereby the developer capacity is significantly impaired or an image generation is no longer possible.
For example, arrangements for cooling of developer units of an electrophotographic printer or copier are known from the documents DE 102 27 575 A1, JP 58083875 and JP 63184774 A.
The heat quantity generated in the fixing unit is only dissipated in part with the carrier material. The remaining portion is typically conducted out from the fixing unit via an exhaust air channel. The waste heat is subsequently optimally guided out from the room (in which the printer is installed) via a ventilation system. A fixing station for fixing of toner images on a recording medium is known from the document DE 28 11 835 A1, in which heat is withdrawn from the recording medium with the aid of a first heat exchanger device arranged at the output of the fixing station. The first heat exchanger device is, connected with a second heat exchanger device arranged at the input of the fixing station, via which second heat exchanger device heat is supplied to the recording medium.
From the document JP 11-338 333 A it is known to arrange a cooling channel around a fixing unit in order to reduce the heat influence on adjacent modules.
From the document U.S. Pat. No. 4,733,272, an image generation device is known in which the fluid of images generated with fluid is dried, whereby the fluid is absorbed by air flowing past. The air containing the fluid is supplied to a heat exchanger and subsequently to a condenser, whereby the fluid contained in the air is condensed and subsequently separated.
A fixing unit for cold fixing of toner images with the aid of a solvent is known from the document US 2004/0126160 A1.
A heat-pressure fixing unit is known from the document EP 1 361 485 A2.
Various absorption refrigerators, in particular Sterling refrigerators and Viulleumier Vuilleumier refrigerators, are known from the document Jungnickel, H. et al., “Grundlagen der Kältetechnik”, Verlag Technik, Berlin, 1990, ISBN 3-341-00806-3.